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Defending Against Jamming and Interference for Internet of UAVs Using Cooperative Multi-Agent Reinforcement Learning with Mutual Information 认领 引用
1
作者 Lin Yan Wu Zhijuan +4 位作者 Peng Nuoheng Zhao Tianyu Zhang Yijin Shu Feng Li Jun 《China Communications》 SCIE EI CSCD 2025年第5期220-237,共18页
The Internet of Unmanned Aerial Vehicles(I-UAVs)is expected to execute latency-sensitive tasks,but limited by co-channel interference and malicious jamming.In the face of unknown prior environmental knowledge,defendin... The Internet of Unmanned Aerial Vehicles(I-UAVs)is expected to execute latency-sensitive tasks,but limited by co-channel interference and malicious jamming.In the face of unknown prior environmental knowledge,defending against jamming and interference through spectrum allocation becomes challenging,especially when each UAV pair makes decisions independently.In this paper,we propose a cooperative multi-agent reinforcement learning(MARL)-based anti-jamming framework for I-UAVs,enabling UAV pairs to learn their own policies cooperatively.Specifically,we first model the problem as a modelfree multi-agent Markov decision process(MAMDP)to maximize the long-term expected system throughput.Then,for improving the exploration of the optimal policy,we resort to optimizing a MARL objective function with a mutual-information(MI)regularizer between states and actions,which can dynamically assign the probability for actions frequently used by the optimal policy.Next,through sharing their current channel selections and local learning experience(their soft Q-values),the UAV pairs can learn their own policies cooperatively relying on only preceding observed information and predicting others’actions.Our simulation results show that for both sweep jamming and Markov jamming patterns,the proposed scheme outperforms the benchmarkers in terms of throughput,convergence and stability for different numbers of jammers,channels and UAV pairs. 展开更多
关键词 anti-jamming communication internet of UAVs multi-agent reinforcement learning spectrum allocation
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Design and optimization of a high-efficiency current-biased reverse load modulated power amplifier with impedance and performance constraints 认领 引用
2
作者 Zhongpeng NI Heng ZHANG +4 位作者 Jing XIA Wence ZHANG Wa KONG Chao YU Xiaowei ZHU 《ENGINEERING Information Technology & Electronic Engineering》 SCIE EI CSCD 2026年第1期71-79,共9页
We propose an optimization method based on evolutionary computation for the design of broadband high-efficiency current-biased reverse load-modulation power amplifiers(CB-RLM PAs).First,given the reverse load-modulati... We propose an optimization method based on evolutionary computation for the design of broadband high-efficiency current-biased reverse load-modulation power amplifiers(CB-RLM PAs).First,given the reverse load-modulation characteristics of CB-RLM PAs,a comprehensive objective function is proposed that combines multi-state impedance trajectory constraints with in-band performance deviations.For the saturation and 6 dB power back-off(PBO)states,approximately optimal impedance regions on the Smith chart are derived using impedance constraint circles based on load-pull simulations.These regions are used together with in-band performance deviations(e.g.,saturated efficiency,6 dB PBO efficiency,and saturated output power)for matching network optimization and design.Second,a multi-objective evolutionary algorithm based on decomposition with adaptive weights,neighborhood,and global replacement is integrated with harmonic balance simulations to optimize design parameters and evaluate performance.Finally,to validate the proposed method,a broadband CB-RLM PA operating from 0.6 to 1.8 GHz is designed and fabricated.Measurement results show that the efficiencies at saturation,6 dB PBO,and 8 dB PBO all exceed 43.6%,with saturated output power being maintained at 40.9–41.5 dBm,which confirms the feasibility and effectiveness of the proposed broadband high-efficiency CB-RLM PA optimization and design approach. 展开更多
关键词 Current-biased reverse load-modulation Broadband High efficiency Power amplifier Optimization
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Security analysis and secured access design for networks of image remote sensing 认领 引用
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作者 Juan Zhao Haibo Dai +3 位作者 Xiaolong Xu Hao Yan Zheng Zhang Chunguo Li 《Digital Communications and Networks》 SCIE EI CSCD 2025年第1期136-144,共9页
The secured access is studied in this paper for the network of the image remote sensing.Each sensor in this network encounters the information security when uploading information of the images wirelessly from the sens... The secured access is studied in this paper for the network of the image remote sensing.Each sensor in this network encounters the information security when uploading information of the images wirelessly from the sensor to the central collection point.In order to enhance the sensing quality for the remote uploading,the passive reflection surface technique is employed.If one eavesdropper that exists nearby this sensor is keeping on accessing the same networks,he may receive the same image from this sensor.Our goal in this paper is to improve the SNR of legitimate collection unit while cut down the SNR of the eavesdropper as much as possible by adaptively adjust the uploading power from this sensor to enhance the security of the remote sensing images.In order to achieve this goal,the secured energy efficiency performance is theoretically analyzed with respect to the number of the passive reflection elements by calculating the instantaneous performance over the channel fading coefficients.Based on this theoretical result,the secured access is formulated as a mathematical optimization problem by adjusting the sensor uploading power as the unknown variables with the objective of the energy efficiency maximization while satisfying any required maximum data rate of the eavesdropper sensor.Finally,the analytical expression is theoretically derived for the optimum uploading power.Numerical simulations verify the design approach. 展开更多
关键词 Image remote sensing Secured access Energy efficiency Sensor transmit power Secured access design
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Passive Integrated Sensing and Communication Scheme Based on RF Fingerprint Information Extraction for Cell-Free RAN 认领 引用
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作者 Yu Jingxuan Zeng Fan +4 位作者 Li Jiamin Liu Feiyang Zhu Pengcheng Wang Dongming You Xiaohu 《China Communications》 SCIE EI CSCD 2025年第1期171-181,共11页
This paper investigates how to achieve integrated sensing and communication(ISAC)based on a cell-free radio access network(CF-RAN)architecture with a minimum footprint of communication resources.We propose a new passi... This paper investigates how to achieve integrated sensing and communication(ISAC)based on a cell-free radio access network(CF-RAN)architecture with a minimum footprint of communication resources.We propose a new passive sensing scheme.The scheme is based on the radio frequency(RF)fingerprint learning of the RF radio unit(RRU)to build an RF fingerprint library of RRUs.The source RRU is identified by comparing the RF fingerprints carried by the signal at the receiver side.The receiver extracts the channel parameters from the signal and estimates the channel environment,thus locating the reflectors in the environment.The proposed scheme can effectively solve the problem of interference between signals in the same time-frequency domain but in different spatial domains when multiple RRUs jointly serve users in CF-RAN architecture.Simulation results show that the proposed passive ISAC scheme can effectively detect reflector location information in the environment without degrading the communication performance. 展开更多
关键词 CF-RAN ISAC passive sensing RF fingerprinting
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A Low Profile Planar Wideband Linearly Polarized Antenna Array Using Planar Dual-Arm Spiral Structures 认领 引用
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作者 Gao Shengqi Hao Zhangcheng 《China Communications》 SCIE EI CSCD 2025年第10期52-59,共8页
In this paper,a 4×4 wideband linearly po-larization(LP)antenna array is proposed by using pla-nar dual-arm spiral structures.Wideband balun struc-tures,composed of microstrip line-fed coupling slots,are adopted t... In this paper,a 4×4 wideband linearly po-larization(LP)antenna array is proposed by using pla-nar dual-arm spiral structures.Wideband balun struc-tures,composed of microstrip line-fed coupling slots,are adopted to feed two dual-arms spiral structures with opposite phases.Then,by combining the left-and right-hand circular polarizations,a linearly polar-ization is achieved.The proposed antenna has a wide operating bandwidth due to the wideband nature of the spiral structure.Simulated results show that the an-tenna element can achieve a 68.73%impedance band-width and a maximum gain of 6.64 dBi within 19.44–38.83 GHz.A 4×4 array prototype is designed to verify the concept.Measured results show that an impedance bandwidth of 63.73%is obtained.The pro-posed array has the merits of a wide bandwidth,a low profile,a low cost,and a small size,which is promis-ing for the application in millimeter wave wireless sys-tems. 展开更多
关键词 microstrip feed millimeter wave planar array spiral antenna wideband
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A Compact Millimeter-Wave,Dual-Band,Dual-Polarized,Duplex,and Scalable Phased Array Enabling B5G/6G Multi-Standard Systems 认领 引用
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作者 Kai Chen Jun Xu +7 位作者 Renrong Zhao Lei Xiang Debin Hou Zhiqiang Yu Jianyi Zhou Jixin Chen Zhang-Cheng Hao Wei Hong 《Engineering》 SCIE EI CSCD 2026年第1期149-162,共14页
A new,compact,and dual-band dual-polarized duplex(D3)phased array architecture is proposed in this study.In contrast to studies reported previously,this design integrates four independent beamforming systems within a ... A new,compact,and dual-band dual-polarized duplex(D3)phased array architecture is proposed in this study.In contrast to studies reported previously,this design integrates four independent beamforming systems within a single printed circuit board(PCB),enabling the proposed 1×4 phased array to transmit or receive simultaneously vertically and horizontally polarized signals at 28 and 38 GHz,thereby supporting concurrent,dual-band,and dual-polarized four-beam operations.In addition,the exceptional frequency selectivity of the phased array facilitates frequency-division duplex operations.By adopting a brick-type architecture,the proposed phased array achieves two-dimensional scalability,which allows it to serve either as a standalone,small-scale phased array,or as a sub-block for larger-scale arrays.A novel,dual-polarized end-fire magnetoelectric dipole antenna was developed as the radiating e lement for the phased array.This antenna exhibits an impedance bandwidth of return loss below-10 d B across the frequency range of 24.8-40.3 GHz(47.6%),which represents one of the broadest operating bands reported for PCB-based,co-apertured,and dual-polarized end-fire antennas.Experimental validation of the fabricated phased array demonstrated that the two orthogonal polarizations could achieve beamscanning ranges exceeding 90°and 60°at 28 and 38 GHz,respectively.The measured effective isotropic radiated power values exhibited distinct frequency selectivities between the two bands.To the best of our knowledge,this is the first demonstration of a D3phased array that presents a promising solution for beyond fifth-generation(B5G)and sixth-generation(6G)millimeter-wave multi-standard systems. 展开更多
关键词 Active phased array Beyond fifth-generation and sixth-generation technology Millimeter wave Dual-band dual-polarized and duplex phased array Wideband end-fire antenna
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Reconfigurable Intelligent Surface Aided Integrated Communication and Localization with a Single Access Point 认领 引用
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作者 Wang Xiyu Huang Yixuan +2 位作者 Yang Jie Han Yu Jin Shi 《China Communications》 SCIE EI CSCD 2026年第1期218-233,共16页
Reconfigurable intelligent surfaces(RISs)not only assist communication but also help the localization of user equipment(UE).This study focuses on indoor localization of UE with a single access point(AP)and multiple RI... Reconfigurable intelligent surfaces(RISs)not only assist communication but also help the localization of user equipment(UE).This study focuses on indoor localization of UE with a single access point(AP)and multiple RISs.First,we propose a two-stage channel estimation scheme where RIS phase shifts are tuned to obtain multiple channel soundings.In the first stage,the newtonized orthogonal matching pursuit algorithm extracts the parameters of multiple paths from the received signals.Then,the LOS path and RISreflected paths are identified.In the second stage,the estimated path gains of RIS-reflected paths with different phase shifts are utilized to determine the angle of arrival(AOA)at the RIS by obtaining the angular pseudo spectrum.Consequently,by taking the AP and RISs as reference points,the linear least squares estimator can locate UE with the estimated AOAs.Simulation results show that the proposed algorithm can realize centimeter-level localization accuracy in the discussed scenarios.Moreover,the higher accuracy of pseudo spectrum,a larger number of channel soundings,and a larger number of reference points can realize higher localization accuracy of UE. 展开更多
关键词 channel estimation indoor localization linear least squares pseudo spectrum reconfigurable intelligent surface
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Visible Region Detection in Ultra-Large-Scale RIS-Assisted Communication Systems under Random Obstacle Environments 认领 引用
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作者 Hu Ying Lin Yuxing +3 位作者 Liu Hao Li Xiao Xu Hao Jin Shi 《China Communications》 SCIE EI CSCD 2026年第5期135-150,共16页
In this paper,we address the visible region(VR)detection problem in ultra-large-scale(ULS)uniform planar array(UPA)reconfigurable intelligent surface(RIS)-assisted communication systems.We propose a practical VR detec... In this paper,we address the visible region(VR)detection problem in ultra-large-scale(ULS)uniform planar array(UPA)reconfigurable intelligent surface(RIS)-assisted communication systems.We propose a practical VR detection method for each individual RIS element even without channel state information(CSI).Furthermore,we introduce an adaptive binary search method that leverages the block characteristics of obstructed region(OR)in two different scenarios:the rectangular OR and the irregular OR.Numerical results demonstrate that the proposed method significantly reduces the detection overhead while achieving a detection accuracy comparable to,or even surpassing,that of the individual detection method.It can achieve accurate VR detection under sufficient transmitting power,even when the CSI is completely unavailable. 展开更多
关键词 ultra-large-scale(ULS)RIS uniform planar array(UPA) visible region(VR)detection
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Radio Propagation and Wireless Coverage of LSAA-Based 5G Millimeter-Wave Mobile Communication Systems 认领 引用 被引量：14
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作者 Haiming Wang Peize Zhang +1 位作者 Jing Li Xiaohu You 《China Communications》 SCIE CSCD 2019年第5期1-18,共18页
Millimeter-wave(mm Wave) communications will be used in fifth-generation(5G) mobile communication systems, but they experience severe path loss and have high sensitivity to physical objects, leading to smaller cell ra... Millimeter-wave(mm Wave) communications will be used in fifth-generation(5G) mobile communication systems, but they experience severe path loss and have high sensitivity to physical objects, leading to smaller cell radii and complicated network architectures. A coverage extension scheme using large-scale antenna arrays(LSAAs) has been suggested and theoretically proven to be cost-efficient in combination with ultradense small cell networks. To analyze and optimize the LSAA-based network deployments, a comprehensive survey of recent advances in statistical mmWave channel modeling is first presented in terms of channel parameter estimation, large-scale path loss models, and small-scale cluster models. Next, the measurement and modeling results at two 5G candidate mmWave bands(e.g., 28 GHz and 39 GHz) are reviewed and compared in several outdoor scenarios of interest, where the propagation characteristics make crucial contributions to wireless network designs. Finally, the coverage behaviors of systems employing a large number of antenna arrays are discussed, as well as some implications on future mmWave cellular network designs. 展开更多
关键词 fifth generation (5G) channel modeling large-scale antenna array(LSAA) millimeter wave(mmWave) communications radio propagation measurements wireless coverage
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A Planar 4-Bit Reconfigurable Antenna Array Based on the Design Philosophy of Information Metasurfaces 认领 引用 被引量：6
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作者 Zheng Xing Wang Hanqing Yang +5 位作者 Ruiwen Shao Jun Wei Wu Guobiao Liu Feng Zhai Qiang Cheng Tie Jun Cui 《Engineering》 SCIE EI CAS CSCD 2022年第10期64-74,共11页
Inspired by the design philosophy of information metasurfaces based on the digital coding concept,a planar 4-bit reconfigurable antenna array with low profile of 0.15λ0(whereλ0is the free-space wavelength)is present... Inspired by the design philosophy of information metasurfaces based on the digital coding concept,a planar 4-bit reconfigurable antenna array with low profile of 0.15λ0(whereλ0is the free-space wavelength)is presented.The array is based on a digital coding radiation element consisting of a 1-bit magnetoelectric(ME)dipole and a miniaturized reflection-type phase shifter(RTPS).The proposed 1-bit ME dipole can provide two digital states of"0"and"1"(with 0°and 180°phase responses)over a wide frequency band by individually exciting its two symmetrical feeding ports.The designed RTPS is able to realize a relative phase shift of 173°.By digitally quantizing its phase in the range of 157.5°,additional eight digital states at intervals of 22.5°are obtained.To achieve low sidelobe levels,a 1:16 power divider based on the Taylor line source method is employed to feed the array,A prototype of the proposed 4-bit antenna array has been fabricated and tested,and the experimental results are in good agreement with the simulations.Scanning beams within a±45°range were measured with a maximum realized gain of 13.4 dBi at12 GHz.The sidelobe and cross-polarization levels are below-14.3 and-23.0 dB,respectively.Furthermore,the beam pointing error is within 0.8°,and the 3 dB gain bandwidth of the broadside beam is 25%.Due to its outstanding performance,the array holds potential for significant applications in radar and wireless communication systems. 展开更多
关键词 4-bit reconfigurable antenna array Information metasurface Digital coding method Low sidelobe Low profile
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DESIGN OF DIGITAL IMPACTING FILTER IN CP-EBPSK WITH RANDOM-POLAR COMMUNICATION SYSTEM 认领 引用 被引量：4
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作者 Jin Yi Wu Lenan +1 位作者 Chen Yifang Yu Jing 《Journal of Electronics(China)》 2012年第3期328-333,共6页
To solve the difficulty of designing digital impacting filter in the receiver of random-polar modulated Extended Binary Phase Shift Keying with Continuous Phase (CP-EBPSK), a design method based on Quantum-behaved Par... To solve the difficulty of designing digital impacting filter in the receiver of random-polar modulated Extended Binary Phase Shift Keying with Continuous Phase (CP-EBPSK), a design method based on Quantum-behaved Particle Swarm Optimization (QPSO) algorithm is proposed. Firstly, QPSO is introduced elaborately, and the basic flow of QPSO is also given. Then, the demodulation principle of digital impacting filter in the communication system of CP-EBPSK with random-polar is demonstrated, and QPSO is utilized to design the digital impacting filter, which also takes the effect of finite word length into consideration when implemented by hardware. Finally, the proposed method is simulated. Simulation results show that the digital impacting filter designed by new method can derive satisfied demodulation performance. 展开更多
关键词 Extended Binary Phase Shift Keying with Continuous Phase (CP-EBPSK) Digital impacting filter Quantum-behaved Particle Swarm Optimization algorithm (QPSO) Demodulation Effect of finite word length
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Research on Channelization Techniques of Radio Astronomical Wideband Signal with Oversampled Polyphase Filter Banks 认领 引用 被引量：1
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作者 Meng Zhang Hai-Long Zhang +3 位作者 Ya-Zhou Zhang Jie Wang Shao-Cong Guo Qiao Meng 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第8期188-205,共18页
Digital channelization decomposes a wideband signal into multiple adjacent sub-bands using Parallel Technology.Channelization can effectively reduce the pressure on the radio astronomy digital backends system and make... Digital channelization decomposes a wideband signal into multiple adjacent sub-bands using Parallel Technology.Channelization can effectively reduce the pressure on the radio astronomy digital backends system and make wideband signal processing possible.Aiming at the problems of signal attenuation at sub-band edge,spectral leakage and aliasing encountered in wideband signal channelization,algorithms to reduce the problems are studied.We design a Critically Sampled Polyphase Filter Bank(CS-PFB)based on the Finite Impulse Response digital filter with a Hamming Window and systematically analyze the frequency response characteristics of the CS-PFB.Based on the channelized structure of the CS-PFB,an Over Sampled Polyphase Filter Bank(OS-PFB)is designed by data reuse,and the filtering frequency response characteristics of CS-PFB and OS-PFB are compared and analyzed.Using the wideband baseband data generated by the CASPSR(Collaboration for Astronomy Signal processing and electronics research Parkes Swinburne Recorder),we implement sub-band division and 16-band output of these data based on the 2×oversampling OS-PFB,and the problem of spectrum inversion in the sub-bands is corrected.After removing 25%of redundant data in the head and tail of each sub-band,we recombine the sub-bands into a wideband.The wideband signal is almost identical to the original observed signal.Therefore,the experimental results show that the OS-PFB can improve the channel response.For the 400 MHz baseband data of J0437-4715,we compare the pulse profile obtained from the original baseband data with the pulse profile obtained after the channelization and recombination.The phase and amplitude information of the pulse profiles are consistent,which verifies the correctness of our channelization algorithm. 展开更多
关键词 (stars:)pulsars general-methods analytical-miscellaneous-methods data analysis
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Analysis of the co-seismic responses of the fluid well pattern system in Jiangsu Province to the Wenchuan and Tohoku earthquakes 认领 引用 被引量：2
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作者 Jiangrong Zheng Haoin Jiang Zhengran He 《Earthquake Science》 CSCD 2012年第3期263-274,共12页
This thesis discusses the earthquake reflecting ability of the observation well pattern system of Jiangsu Province,China,which has been digitally renovated,and probes into the cause of the major differences in the ear... This thesis discusses the earthquake reflecting ability of the observation well pattern system of Jiangsu Province,China,which has been digitally renovated,and probes into the cause of the major differences in the earthquake reflecting abilities of well holes at different measurement points.This is achieved through the analysis of the co-seismic responses to the Wenchuan(2008;Ms8.0,China)and Tohoku(2011;Ms9.0,Japan)earthquakes.We found that the co-seismic response of water level from regional well holes in Jiangsu Province was stronger than that of water temperature.The water-level co-seismic response follows a consistent law and is closely related to the earthquake magnitude.The co-seismic response of water temperature strongly varied among well points,and was more often manifested as a slow restorative change.The co-seismic responses also varied based on tectonic elements.The response in central and northern Jiangsu was weaker than that of southern Jiangsu,possibly due to the thicker loess cover layer in central Jiangsu which makes it less effective at capturing the micro-changes of stress-strain states relative to the hilly land in the south.The more complicated geological structure in southern Jiangsu makes it contribute to greater changes in the state of underground water after a minor disturbance. 展开更多
关键词 fluid well pattern system 2008 Ms8.0 Wenchuan earthquake 2011 MS9.0 Tohoku earthquake features of co-seismic responses
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Secure task offloading strategy optimization of UAV-aided outdoor mobile high-definition live streaming 认领 引用 被引量：1
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作者 Ming YAN Yuxuan ZHANG +2 位作者 Chien Aun CHAN André F.GYGAX Chunguo LI 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2025年第10期201-215,共15页
Unmanned aerial vehicles(UAVs)bring more innovation and attraction to outdoor mobile high-definition(HD)live streaming with its unique perspective.Due to the heavy computational requirements of HD live broadcast tasks... Unmanned aerial vehicles(UAVs)bring more innovation and attraction to outdoor mobile high-definition(HD)live streaming with its unique perspective.Due to the heavy computational requirements of HD live broadcast tasks and the limited hardware performance of UAV equipment,how to reduce the system response delay and improve the energy efficiency of terminal equipment directly affects the secure broadcast of the system.Secure task offloading in this scenario is considered a promising solution and has received academic attention.In this paper,we simulate the UAV-aided outdoor mobile HD live streaming scenarios and optimize the relevant task offloading strategies.First,we design the total cost function of task offloading that jointly optimizes secure time latency and energy consumption.Additionally,we propose a collaborative computing model for multi-UAV task offloading.This model combines the idea of simulated annealing(SA)and introduces the compression factor to enhance the particle swarm optimization(PSO)to realize secure task offloading.The simulation results show that the proposed strategy has better performance in balancing network latency and energy consumption.Compared with the discrete teaching–learning-based optimization(DTLBO)and quantum PSO(QPSO)task offloading strategies,the fitness value of the proposed strategy is decreased by an average of 26.73%and 16.42%,respectively. 展开更多
关键词 Unmanned aerial vehicle(UAV) High-definition(HD)live streaming Secure task offloading Network energy consumption Particle swarm optimization(PSO)
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Design of Power Amplifier for mm Wave 5G and Beyond 认领 引用
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作者 LI Lianming SI Jiachen CHEN Linhui 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2019年第4期579-588,共10页
With targets of cost reduction per bit and high energy efficiency,5G and beyond call for innovation in the mmWave transmitter architecture and the power amplifier(PA)circuit.To illustrate these points,this paper first... With targets of cost reduction per bit and high energy efficiency,5G and beyond call for innovation in the mmWave transmitter architecture and the power amplifier(PA)circuit.To illustrate these points,this paper firstly explains the benefits and design implications of the hybrid beamforming structure in terms of the mmWave spectrum characteristics,energy efficiency,data rate,communication capacity,coverage and implementation technology choices.Then after reviewing the techniques to improve the power amplifier(PA)output power and efficiency,the design considerations and test results of 60 GHz and 90 GHz mmWave PAs in bulk complementary metal oxide semiconductor(CMOS)process are shown. 展开更多
关键词 5G and beyond 6G beamforming complementary metal oxide semiconductor(CMOS) mmWave multiple⁃input multiple⁃output(MIMO) power amplifier transmitter
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Compression and reconstruction of speech signals based on compressed sensing 认领 引用
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作者 梁瑞宇 Zhao li +1 位作者 Xi Ji Zhang Xuewu 《High Technology Letters》 EI CAS 2013年第1期37-41,共5页
Based on the approximate sparseness of speech in wavelet basis,a compressed sensing theory is applied to compress and reconstruct speech signals.Compared with one-dimensional orthogonal wavelet transform(OWT),two-dime... Based on the approximate sparseness of speech in wavelet basis,a compressed sensing theory is applied to compress and reconstruct speech signals.Compared with one-dimensional orthogonal wavelet transform(OWT),two-dimensional OWT combined with Dmeyer and biorthogonal wavelet is firstly proposed to raise running efficiency in speech frame processing,furthermore,the threshold is set to improve the sparseness.Then an adaptive subgradient projection method(ASPM)is adopted for speech reconstruction in compressed sensing.Meanwhile,mechanism which adaptively adjusts inflation parameter in different iterations has been designed for fast convergence.Theoretical analysis and simulation results conclude that this algorithm has fast convergence,and lower reconstruction error,and also exhibits higher robustness in different noise intensities. 展开更多
关键词 compressed sensing （ CS） orthogonal wavelet transform （ OWT） sparse representation reconstruction
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Ionospheric inversion of the Venus Express radio occultation data observed by Shanghai 25m and New Norcia 35m antennas 认领 引用
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作者 Su-Jun Zhang Nian-Chuan Jian +3 位作者 Jin-Ling Li Jin-Song Ping Cong-Yan Chen Ke-Fei Zhang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2015年第9期1559-1570,共12页
Electron density profiles of Venus＇ ionosphere are inverted from the Venus Express （VEX） one-way open-loop radio occultation experiments carried out by the Shanghai 25 m antenna from November 2011 to January 2012 a... Electron density profiles of Venus＇ ionosphere are inverted from the Venus Express （VEX） one-way open-loop radio occultation experiments carried out by the Shanghai 25 m antenna from November 2011 to January 2012 at solar maximum conditions and by the New Norcia 35 m antenna from August 2006 to June 2008 at solar intermediate conditions. The electron density profile （from 110 km to 400 km）, retrieved from the X-band egress observation at the Shanghai station, shows a single peak near 147 km with a peak density of about 2 × 10^4 cm-3 at a solar zenith angle of 94° As a comparison, the VEX radio science （VeRa） observations at the New Norcia station were also examined, including S- and X-band and dual-frequency data in the ingress mode. The results show that the electron density profiles retrieved from the S-band data are more analogous to the dual-frequency data in terms of the profile shape, compared with the X-band data. Generally, the S-band results slightly underestimate the magnitude of the peak density, while the X-band results overestimate it. The discrepancy in the X-band profile is probably due to the relatively larger unmod- eled orbital errors. It is also expected that the ionopause height is sensitive to the solar wind dynamical pressure in high and intermediate solar activities, usually in the range of 200-1000 km on the dayside and much higher on the nightside. Structural variations （＂bulges＂ and fluctuations） can be found in the electron density profiles during intermediate solar activity, which may be caused by the interaction of the solar wind with the ionosphere. Considerable ionizations can be observed in Venus＇ nightside ionosphere, which are unexpected for the Martian nightside ionosphere in most cases. 展开更多
关键词 planets and satellites： terrestrial planets -- planets and satellites： atmo-spheres -- planets and satellites： detection
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A Novel Formal Theory for Security Protocol Analysis of Denial of Service Based on Extended Strand Space Model 认领 引用
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作者 JIANG Rui 《China Communications》 SCIE 2010年第4期23-28,共6页
Denial of Service Distributed Denial of Service （DOS） attack, especially （DDoS） attack, is one of the greatest threats to Internet. Much research has been done for it by now, however, it is always concentrated in ... Denial of Service Distributed Denial of Service （DOS） attack, especially （DDoS） attack, is one of the greatest threats to Internet. Much research has been done for it by now, however, it is always concentrated in the behaviors of the network and can not deal with the problem exactly. In this paper, we start from the security of the protocol, then we propose a novel theory for security protocol analysis of Denial of Service in order to deal with the DoS attack. We first introduce the conception of weighted graph to extend the strand space model, then we extend the penetrator model and define the goal of anti-DoS attack through the conception of the DoS-stop protocol, finally we propose two kinds of DoS test model and erect the novel formal theory for security protocol analysis of Denial of Service. Our new formal theory is applied in two example protocols. It is proved that the Internet key exchange （IKE） easily suffers from the DoS attacks, and the efficient DoS- resistant secure key exchange protocol （JFK） is resistant against DoS attack for the server, respectively. 展开更多
关键词 Denial of Service Security Protocol Analysis Formal Theory, Strand Space Model, Internet Key Exchange
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Intelligent Internet of Things with Reliable Communication and Collaboration Technologies 认领 引用
19
作者 Zhao Junhui Wu Celimuge +4 位作者 Xu Wenjun Qi Chenhao Bu Shengrong Zhang Shuowen Zhang Qingmiao 《China Communications》 SCIE CSCD 2024年第8期I0002-I0006,共5页
The Internet of Things(IoT)connects objects to Internet through sensor devices,radio frequency identification devices and other information collection and processing devices to realize information interaction.IoT is w... The Internet of Things(IoT)connects objects to Internet through sensor devices,radio frequency identification devices and other information collection and processing devices to realize information interaction.IoT is widely used in many fields,including intelligent transportation,intelligent healthcare,intelligent home and industry.In these fields,IoT devices connected via high-speed internet for efficient and reliable communications and faster response times. 展开更多
关键词 interaction Internet IoT
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COMBINATION OF PITCH SYNCHRONOUS ANALYSIS AND FISHER CRITERION FOR SPEAKER IDENTIFICATION 认领 引用
20
作者 Zeng Yumin Wu Zhenyang 《Journal of Electronics(China)》 2007年第6期828-834,共7页
A novel text independent speaker identification system is proposed. In the proposed system, the 12-order perceptual linear predictive cepstrum and their delta coefficients in the span of five frames are extracted from... A novel text independent speaker identification system is proposed. In the proposed system, the 12-order perceptual linear predictive cepstrum and their delta coefficients in the span of five frames are extracted from the segmented speech based on the method of pitch synchronous analysis. The Fisher ratios of the original coefficients then be calculated, and the coefficients whose Fisher ratios are bigger are selected to form the 13-dimensional feature vectors of speaker. The Gaussian mixture model is used to model the speakers. The experimental results show that the identification accuracy of the proposed system is obviously better than that of the systems based on other conventional coefficients like the linear predictive cepstral coefficients and the Mel-frequency cepstral coefficients. 展开更多
关键词 Speaker identification Perceptual linear predictive Pitch synchronous analysis Fisher criterion
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